During cardiac surgery, it is often necessary to introduce a cannula into an artery or other blood vessel. For example, an arterial cannula is typically introduced into the aorta to deliver blood from a bypass-oxygenator machine during cardiopulmonary bypass (CPB), as is used during coronary arterial bypass surgery and other procedures. Such a cannula generally includes a proximal end for receiving blood from the bypass-oxygenator machine, a distal end for entry into the artery, and a lumen extending between the proximal and distal ends.
One concern with such procedures is that calcified plaque or other embolic material may be dislodged during the procedure, particularly when clamping or unclamping the aorta. See Barbut et al., "Cerebral Emboli Detected During Bypass Surgery Are Associated With Clamp Removal," Stroke, 25(12):2398-2402 (1994), incorporated herein by reference in its entirety, which quantifies the level of embolic release during each step of CPB and explains when protection from embolization is needed. Such embolic material may travel downstream, possibly becoming lodged in another portion of the blood vessel or possibly reaching a vital organ, such as the brain, where the material can cause substantial injury to the patient.
In response to this concern, a blood filter device may be introduced into the blood vessel to capture any embolic material that becomes dislodged within the vessel. For example, a blood filter may be disposed on the distal end of an arterial cannula for capturing embolic material in the vessel into which the cannula is introduced. Filters, however, may have certain disadvantages because as blood flows through the filter, the blood may clot and attach to the filter mesh, possibly impairing flow through the filter, and consequently through the vessel. In addition, the filter may become clogged with embolic material during use, preventing the device from effectively capturing additional material and/or impairing flow through the vessel.
Accordingly, there appears to be a need for a device for removing embolic material from a blood vessel, such as the aorta, that avoids these problems.